Our objective is to delineate new pathways for the microbial catabolism of benzenoid compounds; and to isolate, purify and characterize the various enzymes involved. Specifically, enzymes receiving attention currently are 4-hydroxyphenylpyruvate dioxygenase, 4-hydroxyphenylacetate 3-hydroxylase and gentisate dioxygenase. Previous investigations have focused upon pathways in species of Pseudomonas and Acinetobacter but our attention is now directed to other genera in which novel reactions are sought.